Foundation Pit Support Structure Research Articles

Numerical Simulation Study on the Impact of Excavation on Existing Subway Stations Based on BIM-FEM Framework

Building information modeling (BIM) and finite element method (FEM) models have a wide range of applications in underground engineering design, construction, and operation and maintenance. This study employs a BIM-FEM framework to numerically simulate the impact of excavation on existing subway stations, using the Yanjiang New City Station TOD project as a case study. This framework simplifies the smooth integration of BIM and FEM models, automating functions such as assigning material properties, conducting construction simulations, and generating high-quality meshes. Simulation results reveal significant horizontal and vertical displacements in diaphragm walls, support structures, and subway station structures, with the greatest impacts occurring closest to the excavation site. The BIM-FEM framework is validated as an effective tool for designing foundation pit support structures, enhancing numerical modeling accuracy and efficiency in underground engineering. The findings contribute to a better understanding of the dynamic interactions between excavation and underground structures, informing the development of construction strategies and protective measures to ensure structural safety.

Analytical method for calculating internal forces and deformations in foundation pit support under asymmetric loading

Sheet pile walls are significant forms of foundation pit supports that are widely employed in foundation pit support projects in combination with inner bracing. The complex geological conditions, surrounding environments, and earthwork excavations associated with foundation pits generally lead to noticeable asymmetric loading on a support system, posing challenges for accurately calculating the internal forces and deformations. To study the calculation methods for the internal forces and deformations in foundation pit support structures and bracing systems under asymmetric loading, a new model was established for foundation pits subjected to asymmetric unbalanced force loading on opposite sides. This method provides an adjusting technique for bracing forces on both sides based on the principle of equalizing axial forces, thereby providing a calculation approach for the stress and deformation of the foundation pit support system. Additionally, the developed axial force iterative calculation method was compared with numerical analysis methods to analyze the stress and deformation patterns in the support structure, which validated its effectiveness and accuracy.

Experimental study on stress and deformation characteristics of foundation pit considering excavation width using 3D printing technology

A sophisticated model of the foundation pit support structure was developed via a model test that incorporated 3D printing technology. A meticulously scaled-down simulation of foundation pit excavation was conducted, utilizing the excavation width of the foundation pit as the sole variable, to evaluate and compare the impact of various foundation pit widths on the force and deformation characteristics of the foundation pit following layer-by-layer excavation. The findings indicate that the stress and deformation characteristics of the retaining structure shift from the “cantilever” mode to a composite mode of “internally convex” or “concave-convex” as the pit is excavated and internal support is installed. The change in pit width has minimal influence on the mechanical response law of the support structure during excavation. Nonetheless, the alteration in the pit width had a direct effect on both the internal force and deformation of the support structure, as well as the change in surface settlement value. In the experiment, wider pits had monitoring values that increased multiple times compared to narrower pits. The width of the foundation pit has a considerable impact on the mechanical response and stability of the pit, which is evident in the relatively lower lateral earth pressure on the outside of the retaining structure in narrower pits. This results in less stress and deformation of the pit structure. Moreover, the decrease in the passive zone of the pit contributes to better stability, indicating that the lower lateral earth pressure on the outside of the retaining structure is an innate reason for the excellent stability of narrower pits.

Effect of tempering on corrosion properties of mold steel

There are many strongly developed karsts in South China, which bring great uncertainty to the construction stability of underground projects. This paper takes the deep foundation pit project of a station in a sandy soil area as the background, simulates the deep foundation pit excavation process based on finite element software, and comparatively analyzes the influence of the existence of karst holes on the foundation pit support structure. The results show that the effective treatment of solution holes in the process of foundation pit excavation can reduce the risk of surface settlement around the foundation pit but has less influence on the lateral displacement of the foundation pit support structure. The cavity grouting reinforcement technology is also introduced in detail in the paper, which can provide a reference for the reinforcement of deep foundation pit projects in sandy soil stratum containing strong development of large cavities.

Multi-Stage and Multi-Parameter Influence Analysis of Deep Foundation Pit Excavation on Surrounding Environment

As urbanization accelerates, deep excavation projects have become increasingly vital in the construction of high-rise buildings and underground facilities. However, the potential risks to the surrounding environment and the inherent complexities involved necessitate thorough research to ensure the safety of those engineering projects with deep foundation pit excavation and to minimize their impact on adjacent structures. This study introduces a multi-stage and multi-parameter numerical simulation method to scrutinize the construction process of deep foundation pits. This approach not only investigates the influence of excavation activities on nearby buildings and roads but also enhances the fidelity of simulation models by establishing a three-dimensional finite element model integrated with on-site investigated geological information. Therefore, the proposed method can provide a more holistic and accurate analysis of the overall impacts of the pit excavation process. To examine the feasibility and effectiveness of the proposed method, this study adopts the multi-stage and multi-parameter influence analysis approach for a real practical engineering case to explore the impact of excavation on the foundation pit support structure, nearby buildings, and surrounding roads. The foundation pit support’s maximum displacement was 8.64 mm, well under the 25 mm standard limit. Anchor rod forces were about 10% below the standard limit. Building and road settlements were also minimal, at 10.33 mm and 16.44 mm, respectively, far below their respective limits of 200 mm and 300 mm. This study not only validates the feasibility of design and construction stability of deep foundation pits but also contributes theoretical and practical insights, serving as a valuable reference for future engineering projects of a similar scope.

Retracted: Deformation Detection Model of High-Rise Building Foundation Pit Support Structure Based on Neural Network and Wireless Communication

Retracted: Deformation Detection Model of High-Rise Building Foundation Pit Support Structure Based on Neural Network and Wireless Communication

Numerical analysis for supporting and deformation of complex foundation pit groups in unstable areas of karst strata

Due to the extensive karst development zone in karst areas, the stability of the underground soil layer is poor. The support of foundation pits in this area will be affected by complex environmental factors, and if not handled properly, it will cause significant safety hazards and economic losses. In this paper, the three-dimensional finite element model of the complex foundation pit and adjacent foundation pit group was established with the help of Midas GTS NX numerical software, and numerical simulation was carried out for the whole foundation pit excavation and construction process, and the deformation results of the adjacent foundation pit support structure of the complex foundation pit group and the soil outside the foundation pit were obtained. The results show that the underground wall of the complex foundation pit shifted to the north under the action of buttresses, with a similar “cantilever” displacement pattern on the south side of the underground wall in the center, a “push-back displacement” on the north side of the underground wall in the center, and a “ventral” displacement pattern at the corners of the grounded wall and on the east and west sides. Combined with the field measurement data, the support piles in the internal support system have a “cantilever” displacement pattern under the condition of massive soil unloading in the vicinity of the foundation pit, while the supporting piles show a “parabolic” displacement pattern under the action of the corner internal support. The deformation characteristics of the foundation pit in the presence of adjacent pits are significantly different from the results based on empirical laws. The results of the above study will provide useful technical guidance for the safety of excavation support for foundation pit groups in complex environments and the reasonable control of the surrounding environment.

Numerical Simulation Study on Application of T-Shaped Composite Pile Support System in Super-Large Foundation Pit Support Engineering

To reduce the impact of the one-time excavation of deep and large foundation pits on nearby subway tunnels, the excavation should be performed separately; thus, a T-shaped pile support system was studied. First, several foundation pit support structures were compared and selected, and a pile support system was proposed. In terms of space, a T-shaped support structure was formed to reduce the spatial requirements of the foundation pit. Through finite element software, a 1:1 restoration of the foundation pit using a T-shaped pile support system was carried out. The stress characteristics and support effect of the support structure were studied under two working conditions of symmetric and asymmetric excavation. The study found that there was a central effect on the foundation pit using a T-shaped pile support system, that is, the support piles farther away from the center of the T-shaped structure gradually increased the maximum pile bending moment and displacement owing to the constraints of vertical piles and the influence of the pit angle effect, respectively. In the case of symmetrical excavation, the T-shaped structure was simplified into a triangular structure, and the stress form of this type of structure could be reduced to a cantilever double-row pile structure, which met the requirements of pit excavation. The application of a T-shaped pile support structure can provide new design ideas for foundation pit engineering near regional subway lines.

Risk Reduction Measures and Monitoring Analysis of Deep Foundation Pit with Water in a Metro Station in Hefei

The construction of an urban metro will inevitably involve deep excavation. Risk assessment before deep excavation, risk reduction measures, and real-time monitoring during excavation can effectively ensure the safety of deep excavation. Taking the deep excavation pit of Lingbi Road Station of Hefei Rail Transit Line 8 as the research object, this paper first analyses and evaluates the self-risk, groundwater risk, and surrounding environmental risk of the deep excavation pit, and gives the corresponding measures to reduce the risk of the deep excavation pit. Then, the monitoring content of the excavation process is determined according to the environment of the excavation, the hydrogeological conditions, and the type of supporting structure, and the monitoring scheme is designed. Finally, the entire excavation process is monitored in real time. By analyzing the monitoring data of 13 projects, such as horizontal displacement of the wall top, axial support force, groundwater level, etc., it is found that the monitoring values of 13 projects do not exceed the control value. This proves that the composite internal bracing structure of the underground diaphragm wall is suitable for deep foundation pit support in the Hefei area, as the selection of the water-bearing deep foundation pit support structure, the value of the support structure parameters, and the design of the foundation pit dewatering scheme are all reasonable. The study of this paper also serves as a case reference for the support design of water-bearing deep excavation of subway station in Hefei area.

Analysis on intelligent deformation prediction of deep foundation pits with internal support based on optical fiber monitoring and the HSS model

With the continuous expansion of the city scale, while rapidly advancing foundation pit construction, it has become a top priority to prevent the potential safety hazards caused by efforts to catch up with deadlines. In this case, deep foundation pit monitoring can provide important technical support for the foundation pit design and construction safety. However, conventional foundation pit monitoring for point monitoring of structural characteristics cannot accurately locate local strains and related cracks, and cannot provide real-time monitoring of support structures, ordinary soil constitutive models cannot consider the strain hardening characteristics of soft soil. This paper aimed to analyze the characteristics of excavation deformation of a deep foundation pit with internal support in the Dalian Donggang Business District by combining the methods of optical fiber monitoring and finite element simulation. In this study, distributed optical fiber monitoring and routine monitoring were adopted to carry out the synchronous excavation monitoring of foundation pit support structures. The main monitoring objects were the deep horizontal displacement of the support piles and the surface settlement of the foundation pit. Moreover, the authors used the Plaxis finite element software based on the Hardening Soil-small (HSS) model to conduct the numerical simulation analysis, and the results were compared with two groups of the measured data of the deep foundation pit obtained from the aforementioned research. Additionally, in light of the SSA-BP neural network, the back-analysis method of HSS model parameters in the Dalian area is proposed. The findings show that, under the premise of selecting reasonable parameters, the results of finite element analysis of the HSS model, considering the small strain characteristics of the soil, demonstrate a high degree of fit with the actual deformation law of foundation pits, which proves the rationality of the model. Furthermore, it was verified that the distributed optical fiber monitoring has conspicuous advantages in terms of data continuity and accuracy in contrast to routine monitoring. The research results of this paper can provide reference for deformation monitoring and early warning regarding the support structures of deep foundation pits.

Force Calculation of Mechanical Model of Pile-anchored Support Structure Based on Elastic Foundation Beam Method

With the widespread use of deep foundation pit engineering in engineering construction, the force calculation problem about deep foundation pit support engineering has become a common problem in today’s engineering construction process. In this paper, based on the elastic foundation beam method, a simplified mechanical model of pile-anchored structure is proposed, and a systematic and practical calculation method is proposed for the force and deformation calculation of deep foundation pit support structure. The method simplifies the support structure as a vertically placed elastic foundation beam, the support, anchor and geotechnical body are replaced by a spring system, the spring stiffness of geotechnical soil can be calculated by the deformation modulus of geotechnical soil, and a systematic calculation method is proposed for the dynamic characteristics of the construction and structure of the foundation pit project; Based on the monitoring data of a deep foundation pit project, the calculation method of the simplified mechanical model proposed in this paper is verified, and the theoretical calculation value is compared with the field monitoring results; Single factor analysis is carried out on the detailed parameters of pile-anchor supporting structure to study the influence of cable prestress, cable dip Angle, pile diameter, pile length and other related parameters on the deformation and stress characteristics of supporting structure. Then the orthogonal combination of all factors is carried out to propose the optimization design. The results show that the maximum settlement deformation of the calculated value is 23.437 mm, and the maximum settlement deformation of the monitored value is 26.517 mm, and the difference between them is small. The maximum bending moment is 1210 kN⋅m after 150 kN and 250 kN horizontal prestressing is added to the second- and third-layer anchors respectively. After optimization, the maximum bending moment of pile row is 336.87 kN⋅m, and the maximum horizontal displacement of pile body is 16.505 mm, which is reduced by 11.97% compared with the original design.

Influence of Construction Sequence on the Force Characteristics of Foundation Pit Support Structure

Influence of Construction Sequence on the Force Characteristics of Foundation Pit Support Structure

Experimental Study on the Flexural Behavior of Connected Precast Concrete Square Piles

Part of deep foundation pit support engineering needs to select connected precast concrete square piles (CPCSPs). Under the premise that the quality of precast concrete square piles (PCSPs) meets engineering requirements, the quality of CPCSPs becomes the key factor to ensure the safety of foundation pit support structures. This paper puts forward a new connection technology of CPCSPs and carries out the flexural behavior experiment of unconnected precast concrete square piles (UPCSPs) and CPCSPs. The distribution of crack and strain on different surfaces of UPCSPs and CPCSPs are measured by carbon fiber composite strain sense optical cables, glass fiber composite strain sense optical cables, and fixed-point polyurethane strain sense optical cables. The anti-crack load, ultimate load, bending moment, and flexural deformation of UPCSPs and CPCSPs are measured. The experimental results of UPCSPs and CPCSPs are compared. The results show that the anti-crack strength of CPCSPs is greatly increased while the flexural deformation of CPCSPs is decreased before the occurrence of crack. With the development of crack (failure stage), the outside areas of hoop steel plate exhibit cracks. At this moment, the strength of CPCSPs is no longer controlled by the strength of middle areas. The ultimate strength of CPCSPs is basically equivalent to that of UPCSPs. The ultimate bending moment of CPCSPs is higher than its design value (about 66%∼76%). The selection of CPCSPs in the design of foundation pit support has good reliability.

Numerical Simulation of Anchorage Force and Deformation of Pile in Deep Mixed Soil Foundation Pit

Foundation pit support plays a pivotal role in the process of urbanization in our country. The emergence of new support forms has dramatically enriched the diversity of foundation pit support. The pile-anchor support structure is a new type of support structure that has emerged with the development of foundation pit engineering in recent years. However, the current theoretical research on the foundation pit pile-anchor support system often cannot meet the improvement of the on-site construction technology level, and many calculation models based on assumptions cannot truly reflect the relationship between the foundation pit support structure and the soil layer, and the piles The stress and deformation characteristics of the anchor support system itself[1]. With the rapid economic development and the continuous expansion of the urban construction scale, the foundation pit problem caused by high-rise buildings and underground traffic has become a hot issue in civil engineering. Foundation pit accidents often occur due to design errors. 3D numerical simulation can better simulate the whole process of foundation pit excavation and support, and provide displacement and internal force prediction data for actual construction, thereby effectively preventing foundation pit accidents. Midas finite element software performs numerical simulation analysis of deep foundation pit support. Through further analysis of vertical deformation and horizontal displacement, the deformation value of the supporting structure is extracted and compared with the measured deformation value to guide the deformation control design and engineering monitor.

Deformation Detection Model of High-Rise Building Foundation Pit Support Structure Based on Neural Network and Wireless Communication

The reasonable selection and optimized design of the deep foundation pit support scheme is directly related to the safety, construction period, and cost of the entire project. Here, based on a large number of theoretical results in many related fields, relevant influencing factors are systematically analyzed, and advanced mathematical algorithms such as neural networks are introduced according to the relevant characteristics of building deep foundation pit support construction. First of all, this paper designs and implements deep foundation pit construction safety risk technology based on wireless communication and BIM technology and analyzes and describes the framework and function of the foundation pit construction safety risk identification system. Secondly, we use neural network algorithms to study the deformation prediction of the foundation pit supporting structure, which can describe the expression method of the above safety knowledge. Finally, the differences and benefits of this method and traditional methods are compared through experiments, which show that this technology can pave the way for the construction of deep foundation pit construction safety risk knowledge.

Effect of genetic algorithm in optimizing deep foundation pit supporting structure

To design a deep foundation pit support structure that can guarantee safety and obtain the highest economic benefit under the premise of meeting the engineering requirements, the realization method of genetic algorithm and the calculation method of safety factor in the optimal design of pile-anchor supporting structure of deep foundation pit were proposed in this study, and the optimization design system of pile-anchor supporting structure of deep foundation pit was designed according to the rules of survival and fittest of genetic algorithm. According to an actual engineering case, this system is used for optimized design and compared with the original design results. The results showed that the construction cost of the deep foundation pit supporting structure with optimized design had been reduced from 6920 to 4760 yuan. It not only saved about 32.5% of the project cost, the safety coefficient also reached above 1.25, which met the technical regulations of the foundation pit support in China. This study provided an important reference for the application of genetic algorithms in the field of foundation pit engineering.

Foundation Pit Support Structure under Special Geotechnical Structure

Due to The Vast Territory of China, The Topography, Geological Conditions and Surrounding Environment of the Construction Project are Very Different. The Design and Construction of the Foundation Pit Support Project is One of the Most Closely Integrated Engineering Measures Combined with the Above Conditions. The Design and Construction of Deep Foundation Pit Support Engineering in Special Geotechnical Areas Has Become One of the Most Complicated Technical Problems in the Field of Civil Engineering Construction. Based on the Above Background, The Purpose of this Paper is to Study the Foundation Pit Support Structure Under Special Geotechnical Structure. This Paper Compares and Analyzes the Materials and Structure Types that Can be Used for Foundation Pit Support, And Concludes that Bamboo is an Economical and Environmentally Friendly New Material, Its Output Large, Good Mechanical Properties, Can Be Used For Temporary Support of Shallow Foundation Pits. It is Proposed to Use the Bamboo Tube as the Foundation Pit Support Material, And it is Applied in the Soft Soil Layer Foundation Pit Support Project in the form of Row Pile Support Structure. In this Paper, the Top Displacement of the Bamboo Pipe Pile is Larger than that of the Steel Pipe Pile, But the Maximum Pile Top Displacement of the Bamboo Pipe Pile is 1.8mm. The Maximum Displacement of the Pile Top is 18mm, The Displacement is Small, Within the Allowable Range, and in the Actual Project, the Pile Top is Generally Constrained to Further Control the Displacement of the Pile Top to Ensure the Safety and Stability of the Foundation Pit.

Application and Research of Soil Mixing Wall

Soil Mixing Wall can meet the needs of foundation pit support structures in various projects. Compared with other supporting structures, it has the advantages of good permeability resistance, short construction period, and less impact on the surrounding environment. It is a foundation pit supporting structure with great development potential<sup>[1]</sup>.

Application of Deep Foundation Pit Support Technology Based on Big Data Analysis in Construction Engineering Construction

In recent years, the rapid development of deep foundation pit support projects has become an important problem in urbanization construction. The role of deep foundation pit support projects in the construction and development of large and medium-sized cities has become increasingly important. In order to ensure the safety of foundation pit engineering and avoid accidents, people not only need to strengthen supervision in survey, design, construction and other aspects, but also apply monitoring technology to foundation pit engineering, so that engineering and technical personnel can master the dynamic changes of foundation pits. Improve the early warning capability of foundation pit engineering. In this paper, by using big data internet thinking and deep foundation pit support technology, real-time monitoring simulation prediction of foundation pit support structure in building construction is performed. Use big data to make a comparative study on the application scenarios of deep foundation pit technology in building construction, and use mathematical analysis and mathematical statistics to verify the collected data, so as to achieve the purpose of monitoring and prediction. So as to lay a theoretical foundation for the formulation of foundation pit support construction plans and foundation pit monitoring construction plans.

Discussion on Monitoring Method for Horizontal Displacement of Supporting Pile Top of Deep Foundation Pit in Urban Rail Transit Project

The horizontal displacement monitoring of the supporting piles plays a vital role in the safety judgment of deep foundation pit excavation and construction of main structure. In urban rail transit engineering, the monitoring of horizontal displacement of retaining pile top of deep foundation pit should be carried out according to the characteristics of the project, formulated a scientific monitoring plan, and selected a reasonable monitoring method. If necessary, the monitoring methods should be optimized and integrated, so as to get the real and effective monitoring data, which can reflect the change of the horizontal displacement of the foundation pit support structure to the greatest extent. By analyzing several common methods of deep foundation pit monitoring in current urban rail transit projects, the advantages and disadvantages of each method are summarized, and reasonable suggestions are proposed for accurate monitoring.